# Flags & environment
This page summarizes runtime flags and environment variables that affect DCR behavior.
## Build/run flags
Used with `dcr build` and `dcr run`:
- `--debug`: select debug profile.
- `--release`: select release profile.
- `--force`: ignore incremental cache checks and rebuild.
- `--clean`: remove `target/<profile>` and `build.clean` paths before build.
Notes:
- Flags can be passed in any order.
- Duplicate profile flags are rejected.
## Clean flags
Used with `dcr clean`:
- `--debug` / `--release`: clean only selected profile directory.
- `--all`: in workspace root, also clean all members.
## Environment variables
Tool selection overrides:
- `DCR_COMPILER` (all languages)
- `DCR_CC`, `DCR_CXX`, `DCR_AS`, `DCR_AR`, `DCR_LD`
Diagnostics:
- `DCR_DEBUG=1` enables verbose build logging.
## Quick examples
```sh
# Force full release rebuild
dcr build --release --force
# Clean before debug run
dcr run --clean --debug
# Use custom compiler from env
DCR_CC=clang-18 dcr build --debug
```